This invention pertains to a method for collision avoidance in local Ethernet networks, such as a home automation network, having a personal computer and a plurality of control devices attached. In such a network, when a management message is broadcast from the host personal computer to all connected control devices, each one of such devices must reply with a response to the host computer. There is, however, a probability that responses might collide, leading to data loss. The present invention discloses a method to generate delayed responses to the sender from each control device, where an individual device's delay is computed in accordance to a unique value contained in its MAC address. The method will guarantee different delay times for all attached control devices, and hence a collision-free operation.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for collision avoidance in Ethernet networks, the method comprising the following steps: having a network with a network management device and a plurality of control devices, using an Ethernet standard; having each control device implement basic management functions executed by an embedded processor means; having said network management device send a broadcast message to all of the control devices; having each of said control devices send a response to said broadcast message depending on a unique time delay using the value in a unique byte of a control device's MAC address as an initial value of a counter; decreasing counter until counter value reaches zero at which time said control device sends said response; having said broadcast message contain an adjustment parameter, whenever applicable, to set an upper limit to the value of said counter.
2. A method as in claim 1 further comprising an Ethernet hub.
3. A method as in claim 1 including having each count last between 600 microseconds and 1 millisecond.
4. A method as in claim 1 including avoiding collisions of response messages by including unique, deterministic delays generated in each control device.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
March 2, 2005
April 20, 2010
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